Nakiri Knife Sample Approval Checklist Before Production

Start With The Approved Spec Sheet

Before you touch the sample, put two papers on the QC table first: the buyer brief and the factory quotation. Then lay the technical drawing beside them and check every dimension with a 0.01 mm digital caliper. In 7 out of 10 sample disputes we see, nobody is cheating. The sheet says “Japanese vegetable knife,” the buyer pictures one nakiri profile, and the nakiri knife factory cuts a different outline on the grinding line.

Your approved spec sheet should spell out the measurable points: blade length and height in mm, spine thickness at heel and mid-blade, steel grade, target HRC, handle material, finish, logo method, packaging, carton quantity, and inspection standard. For a private label retail team, this is not paperwork. It is the contract language your QC inspector will use 40 days later, when QC pulled the sample and checked it against AQL 2.5 instead of someone’s memory. The buyer may argue over “close enough”; that is the wrong question to ask.

For a typical 6.5 inch nakiri, approve 165 mm blade length, 50 mm blade height, 2.0 mm spine at heel, 1.2 mm at mid-blade, and 180-220 g finished weight. Want a lighter Western-style retail product? Put the target weight on the PO. Want a taller, heavier vegetable cleaver feel? Write it down, because a 50 mm blade and a 58 mm blade do not sell the same on a shelf. We once saw a PO typo change 165 mm to 155 mm, and the buyer caught it only after the pre-shipment photos.

At TANGFORGE, a custom nakiri knife sample is checked against a tolerance sheet before it leaves our China factory. For mature designs, we suggest dimensional tolerance of ±1.5 mm on blade length, ±1.0 mm on blade height, and ±10 g on weight. We run tighter tolerances when the order value supports it, but the math doesn't work for every order: the rejection rate climbs fast, and one batch we measured had 13 handles pulled for being 0.8 mm proud at the bolster. That came off the caliper bench, not theory.

Confirm whether the sample is a concept sample, sales sample, or pre-production sample. A concept sample proves direction. A pre-production sample must match final steel, heat treatment, handle, logo, packaging, and carton labeling. Do not approve a handmade sample for mass production unless the nakiri knife manufacturer confirms which batch-production details will change; we have seen this go sideways when the buyer flagged a carton label typo only after 36 cartons were packed. The inkjet code on the outer carton should match the approved sheet, every time.

Check Blade Geometry Like A Factory

The nakiri does not hide bad geometry. Its straight edge shows every miss. Put the sample on a flat PE cutting board, press lightly at the heel, and check for daylight under the middle or tip. We run this check with a 0.10 mm feeler gauge when QC pulls the sample. A proper nakiri should keep a mostly flat cutting line, with a small tip lift only if your market already approved that profile. If the middle sits high, the buyer hears the same complaint within 30 days: cabbage and scallions stay joined at the bottom. Do not skip this check.

Measure heel height and spine thickness with digital calipers, not sales-desk photos. Photos hide too much. A 48 mm blade and a 53 mm blade sit in different shelf positions, and we have seen buyers reject cartons because the knife looked closer to a mini cleaver than the approved nakiri. A spine at 2.5 mm instead of 1.8 mm changes the cut feel and makes the knife look cheap when the color box says “precision slicing.” The math does not work. On the inspection table, we check the heel with a Mitutoyo caliper before we sign off.

Match the edge angle to the steel and the end user. For a mass retail stainless nakiri, 15-18 degrees per side is normal, and QC can confirm it with a simple edge angle gauge at the packing bench. For harder Japanese-style steel, 12-15 degrees per side cuts cleaner, but the carton insert needs clear care wording and the blade needs better tip protection. For a wholesale club or general kitchen line, edges ground too thin bring returns. We have seen this go sideways after one buyer pushed for a “razor feel” on a low-price SKU. The buyer flagged it after 200 pieces chipped in drop testing.

Ask the nakiri knife supplier to write the sharpening method on the sample report. Belt ground? Hand finished? Stone finished? Is the final edge polished or left toothy? You do not need lab wording for every SKU, but you need the factory to repeat it on 3,000 pieces, not just one showroom sample. If the first sample cuts well because one senior worker sharpened it slowly by hand, while bulk production runs through the grinding line at production speed, the approved sample is not a production standard. We shipped a batch once where the PO typo said “polish edge,” and the buyer meant “polished spine” instead.

Approve Steel, HRC, And Finish

Steel choice is where 6 out of 10 private label teams overbuy. A nakiri is for vegetables, not frozen chicken bones. Asking for the hardest blade is the wrong question to ask. If the end user cuts on glass boards, puts knives in dishwashers, or drops them loose into a drawer, stainless at 56-58 HRC usually brings fewer complaints than a 61 HRC blade with a chipped edge. We saw this on a 2024 sample run: QC pulled the sample after the buyer flagged micro-chips at the tip under a 10x loupe, then the grinding line found the edge was too thin at the last 8 mm.

Common choices for nakiri knife wholesale programs include 3Cr13, 5Cr15MoV, 7Cr17MoV, X50CrMoV15, AUS-10, 10Cr15CoMoV, and Damascus clad constructions. For entry retail, 5Cr15MoV at 55-57 HRC is acceptable when the FOB target is tight and the MOQ is built around carton efficiency. For mid-tier private label, 7Cr17MoV or X50CrMoV15 around 56-58 HRC gives a safer balance between edge holding and return risk. For premium, AUS-10 or 10Cr15CoMoV at 59-61 HRC works only if the insert card clearly says hand wash, dry fast, and use a wood or plastic board. No vague wording. The grinding line checks blade thickness at the spine with a digital caliper before polishing, and we normally want the spine and edge geometry written on the sample tag, not left in someone’s chat history.

Ask for the exact HRC test position and sample quantity. One blade from a hand sample proves almost nothing. For bulk production, we normally check 3-5 blades per lot during heat treatment confirmation, then record the HRC band in the QC file. TANGFORGE’s Yangjiang production team keeps kitchen knife HRC within a 2-point band when steel and heat treatment are locked. We run the Rockwell tester near the heel after tempering. If the reading jumps outside the agreed band, the lot stays back before handle assembly, because fixing a hardness miss after riveting is wasted labor and the math doesn’t work.

Surface finish also needs approval. Satin, mirror, stonewash, black coating, and Damascus etching do not behave the same under retail lighting. A brushed satin finish hides small handling scratches better than mirror polish, which matters after 200 pieces pass through packing gloves and PE bags. Black coating looks strong on shelf, but define the adhesion test, the coating thickness in mm if your spec requires it, and whether any coated area contacts food. For EU retail, confirm REACH and LFGB expectations early. For North America, FDA food-contact expectations and correct material declarations are usually requested by importers. On the packing table, QC will still catch fingerprints and uneven etching under a 6500K inspection lamp, so approve the finish under normal light before the order goes into mass polishing.

Do not approve a blade finish from one beauty photo. Ask for front and back images, a spine shot, a choil shot, and a close-up logo image under normal light, not just the studio shot with the reflection hidden. We've seen this go sideways when a PO typo changed “satin” to “mirror,” and the buyer noticed only after the pre-shipment photos. If possible, keep one signed physical sample at your office and one sealed reference sample at the nakiri knife manufacturer in China. We ship against that sealed sample, not against a filtered catalog photo.

Handle Fit Decides Retail Quality

Most retail buyers skip steel chemistry, but they see a handle gap in 3 seconds. On a nakiri, the wide blade face sits close to the handle, so a poor front joint shows more than it would on a petty knife. Check the handle first. We have seen buyers approve the satin blade, then reject the sample after QC pulled a 0.3 mm shadow line at the front scale under the bench lamp.

For full tang designs, check rivet alignment against the drilled holes and compare left-right scale thickness with a caliper. Then run a fingernail along the exposed tang, the polished spine, and the handle front where buffing compound often hides. A gap over 0.2 mm can collect food residue and trigger hygiene complaints. For hidden tang or Japanese wa-handle designs, check the blade insertion angle, ferrule seat, glue overflow, and whether the handle centerline follows the blade centerline from heel to tip. On our bench, we use a 0.2 mm feeler gauge and a simple centerline jig; the eye misses too much when 20 samples land before lunch.

Handle material has to fit the sales channel. Pakkawood gives a stronger shelf look, but moisture control and clean buffing matter, especially around the ferrule face. G10 stays stable and takes abuse, but a 3,000 pcs order can run 8% to 12% above the buyer’s target price. PP or TPR works for supermarket and promo lines if the mold parting line is trimmed clean and the texture does not feel like toy plastic. Natural wood needs honest care labeling and tight color grading, not mixed dark and pale handles in the same 6-piece counter display. If your retail customer wants dishwasher-safe claims, do not overpromise on wood handles or decorative finishes; after 50 wash cycles, the claim starts to fall apart. We run that test with a rack in the washroom, and cheap handles expose themselves fast.

Balance is not just a chef preference. It changes perceived quality during unboxing. A 165 mm nakiri with a Western handle often balances near the heel or slightly behind it. A wa-handle version can feel more blade-forward. Neither is wrong. Approve it on purpose. Ask your nakiri knife supplier to record finished weight and balance point from the heel, for example 205 g and 10 mm behind heel. We mark it with a ruler on the QC table because “feels balanced” on a sample report is the wrong answer, and the math does not survive buyer pushback.

Check smell before approval. Low-grade handle material, weak glue, or rushed finishing can leave odor inside retail packaging. Open the sample after it has been sealed for 48 hours. If one sample smells strong, a full container can smell worse after 30 days at sea. We had one PO where the buyer flagged “chemical smell” during carton inspection, and replacing 600 handles took 12 days vs 18 days for a full remake. The grinding line had already signed off the finish, so the problem sat in packing, not in the blade.

Test Cutting Performance And Safety

A sample does not need a lab report before every order, but it must cut real vegetables on our bench. We run the same 5-point check each time: tomato skin without sawing, carrot push cut on a 25 mm section, onion slices checked for wedge cracking at the cut face, cabbage chopping on a PP board with the same stroke count, and an 80 gsm paper cut after 10 minutes of use. No chef show. The point is to compare sample round one, sample round two, and the pre-production sample under the same routine, with the same test board and QC sharpness note sheet. We keep the board beside the grinding line. The result is easy to read.

For a retail nakiri, out-of-box sharpness should not jump from carton 1 to carton 20. If you use CATRA testing, set the target with the factory before sampling because CATRA results change with blade steel, edge angle, and sharpening finish. If you do not use CATRA, define a pass/fail test: clean slicing on 80 gsm paper and push-cutting tomato skin without sawing. We have seen buyers ask for “sharper” after sampling, but that is the wrong question to ask. Tell us the edge angle, for example 15° per side or 18° per side, and the grinding line can hold it with a gauge instead of guessing by hand. One bad PO note can throw the whole batch; we once saw “18°” typed as “13°” on a sample comment sheet.

Safety checks need the same discipline as sharpness. Run a cut-resistant glove along the spine and heel area, then check the choil and handle front under a desk lamp. Burrs show up fast. Sharp corners on the spine, choil, or handle front create complaints even when the edge passes, so QC pulled the sample with a glove first and a fingertip check second. Check the tip profile too. A nakiri has a squared tip, but it should not have a fragile needle corner that bends inside the PE sleeve or pokes the color box during transit. We once pulled a sample with a 0.3 mm burr on the heel, and the buyer flagged it in 10 minutes.

Drop and torque should be agreed before bulk approval. For full tang knives, the handle should not loosen after moderate impact, and QC should pull the sample again after the test instead of only checking it before packing. For plastic handle designs, the welding, overmolding, or rivet structure must survive normal kitchen use; we normally check for handle gap over 0.2 mm after twisting by hand with a rubber pad. For premium gift sets, check the knife inside the box after a 1 m carton drop simulation. If the blade moves and cuts the insert, the packaging is not ready. The math does not work if you approve a nice blade and then pay for 300 retailer returns because the tray was too soft. We ship enough cartons to know one weak insert can wreck the set.

When we prepare pre-production samples in Zhejiang-related export documentation or Yangjiang factory files, we normally attach cutting notes, safety remarks, and packaging photos together. One file, one decision. We also mark the PO style number and carton version on the photo page, because one buyer once flagged a handle color mismatch caused by a single typo on the PO. This lets your retail private label team approve one complete product, not a pretty blade with open risks. Keep the file with the sample box, and the next round can move in 12 days instead of 18 days.

Verify Branding, Packaging, And Compliance

Private label problems often show up after the knife is approved. The blade passes. Then QC pulls the fully packed sample and finds the logo sitting 3 mm too low, the barcode failing on a Zebra scanner, the care card listing the wrong steel grade, or the carton mark copied from an old PO typo. Put branding and packaging inside the nakiri knife sample approval checklist, not in a separate email thread.

Approve the logo method on the final blade finish. Laser engraving on satin stainless gives a clean mark and holds up under normal washing. Pad printing costs less on some boxes and handle marks, but we run a 3M tape rub test before signing it off. Etched Damascus logos look patchy when the etching depth is not controlled; QC pulled one sample where the left side looked darker than the right by about 20%. Specify logo size, position from heel or spine in mm, color if used, and whether the logo appears on one side or both sides.

Test the packaging with the real knife, not an empty box. For e-commerce, the insert must stop blade movement after a drop test. For retail hanging cards, buyers often flag knife weight, hook hole tearing, or a weak anti-theft tie after one shake test. For gift boxes, check magnetic closure strength, foam density, sleeve fit, and whether the blade edge touches paperboard. If you use Amazon FNSKU, UPC, EAN, suffocation warning, country of origin, or multilingual care labels, verify each one on the physical sample with a scanner and a ruler.

Compliance depends on the selling market. EU buyers ask for REACH and LFGB, and some also want BSCI or ISO 9001 factory documentation before deposit release. North American importers ask for FDA food-contact declarations, Prop 65 review for California, and carton labels that match their warehouse system. If your nakiri knife manufacturer cannot send documents before bulk production, waiting until shipment is the wrong question to ask. We’ve seen this go sideways during final inspection when the buyer flagged a missing origin label on the master carton.

At TANGFORGE China, we ask buyers to approve a packaging dieline and one fully packed sample before mass production. For new private label projects, custom packaging adds 10-18 days to the schedule; a plain white box might clear in 12 days, while color proofing plus insert adjustment can push it to 18 days. The grinding line can keep moving. Printing does not care about your vessel closing date, and the math does not work if artwork approval lands after the cartons are already on press.

Lock QC Limits Before Mass Production

The signed sample is not a bulk-quality contract by itself. Lock the inspection limits before we run steel. We’ve had batches match the golden sample in the QC cabinet, then drift on the line: handle color moved half a shade, spine thickness changed by 0.3 mm, logo etching cut deeper after the operator changed the pad. Decide what passes, what gets reworked, and what stops shipment before the first coil is cut.

Write defect categories on the QC sheet in plain factory language. Critical defects should include a cracked blade, wrong steel grade, loose handle, sharp burr outside the cutting edge, oil or dust contamination, wrong logo brand, and packaging that can injure the user. Major defects can include handle gaps checked with a 0.2 mm feeler gauge, sharpening that fails the paper-cut test, carton marks that do not match the PO, blade warpage beyond tolerance, or surface scratches that show under normal shop light. Minor defects can include light polishing marks, slight color variation in natural handles, or small box scuffs that still pass retail shelf review. QC pulled the sample once and the buyer flagged a 0.2 mm handle gap. Good catch. That is the kind of call that saves a claim later.

For retail knife orders we ship, AQL 2.5 for major defects and AQL 4.0 for minor defects is practical on 600-1,200 pcs runs. Critical defects should be 0. If your retailer requires AQL 1.5, tell the factory before pricing, not after the PI is signed. The math does not work if QC checks the packed goods, finds 8 borderline handle gaps, and the buyer only then asks for tighter inspection. Stricter AQL means more inspection hours and more rework, so the unit cost usually moves.

Set production checkpoints. For a new custom nakiri knife, we recommend confirming the first 20-30 pcs off the line before full assembly, then checking grinding, heat treatment, handle assembly, polishing, sharpening, and final packing at separate points. On the grinding line, QC should check blade profile against the signed sample with a caliper before 1,000 pcs are already shaped. A third-party pre-shipment inspection should use the signed pre-production sample, not only the purchase order. We’ve seen this go sideways when the PO had one typo on the handle spec and nobody caught it until packing.

Lead time should also be locked. At TANGFORGE, typical MOQ for a private label nakiri is 600-1,200 pcs per SKU depending on handle, packaging, and steel. Normal bulk lead time is 35-55 days after deposit and final sample approval. Our Yangjiang production capacity for kitchen and outdoor knives is about 500,000 units per month across categories, but custom tooling, Damascus steel, and printed packaging can still block the schedule. We had a 35-day plan turn into 49 days because the color box supplier printed the barcode one digit wrong on the first batch. Packaging is not a side job.

The final approval email should be boring and precise: sample version, date, steel, HRC band, dimensions, logo file, packaging file, carton mark, AQL level, shipment term such as FOB China or DDP, and approved photos. Attach the front, spine, handle joint, logo, and master carton photos from the approved sample set. Boring approval records prevent expensive arguments. One clean email beats three calls after the goods are on the water.

Frequently asked questions